Photometrically modulated delivery of reagents

ABSTRACT

A process system adapted for processing of or with a material therein. The process system includes: a sampling region for the material; an infrared photometric monitor constructed and arranged to transmit infrared radiation through the sampling region and to responsively generate an output signal correlative of the material in the sampling region, based on its interaction with the infrared radiation; and process control means arranged to receive the output of the infrared photometric monitor and to responsively control one or more process conditions in and/or affecting the process system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 11/445,755filed Jun. 2, 2006 for “Photometrically Modulated Delivery of Reagents,”issuing May 13, 2008 as U.S. Pat. No. 7,373,257, which is a continuationof U.S. patent application Ser. No. 11/157,760 filed Jun. 21, 2005 for“In-Situ Gas Blending and Dilution System for Delivery of Dilute Gas ata Predetermined Concentration,” issued Jun. 6, 2006 as U.S. Pat. No.7,058,519, which in turn is a continuation of U.S. patent applicationSer. No. 10/641,576 filed Aug. 14, 2003 for “In-Situ Gas Blending andDilution System for Delivery of Dilute Gas at a PredeterminedConcentration,” issued Jun. 21, 2005 as U.S. Pat. No. 6,909,973, whichin turn is a continuation-in-part of U.S. patent application Ser. No.10/402,759 filed Mar. 28, 2003 for “In-Situ Gas Blending and DilutionSystem for Delivery of Dilute Gas at a Predetermined Concentration,”issued Jun. 20, 2006 as U.S. Pat. No. 7,063,097. The disclosures ofthese prior applications and patents are hereby incorporated herein byreference, in their respective entireties.

FIELD OF THE INVENTION

The present invention relates to apparatus and method forphotometrically modulating the delivery of reagent, e.g., in asemiconductor manufacturing operation including processing of or withsuch reagent. In a specific aspect, the invention relates to supply ofreagent gas deriving from solid and/or liquid sources.

DESCRIPTION OF THE RELATED ART

The semiconductor industry uses a wide variety of reagent gases inapplications where the source materials for such reagent gases are solidand/or liquid in character. Such source materials may be highly toxic orhazardous and the dosage of active gas species may in some instances bevery small.

When solid and/or liquid source materials are employed, metering thedelivery of such non-gaseous materials to a semiconductor processingtool is difficult. Typically, the non-gaseous material is bubbled orswept from a vessel containing the material, by means of a carrier gasthat is flowed through the vessel to entrain the vapor of the sourcematerial. The resulting carrier gas/active material vapor is thentransported as a feed gas stream to the semiconductor tool.

The feed gas stream is flowed to the tool through flow circuitryincluding lines that typically are heated to prevent condensation and/orfreezing of the reagent in the piping, valving, etc. of such flowcircuitry.

In design and construction of the semiconductor process system includingsuch tool and the delivery system for the solid and/or liquid sourcematerial, it is often necessary to rely on published vapor pressurevalues for the source material in order to estimate the delivery rate ofthe source material. Vapor pressure curves in the literature, however,relate to steady state conditions involving vapor-saturated streams.They do not take into account time-varying fluctuations in sourcematerial delivery rate, such as may be attributable to (i) changes inliquid levels in the system that may result in non-saturated vaporstreams, (ii) concentration spikes that can occur during initial openingof carrier gas valves, (iii) changes in the rate of vaporized materialderiving from changes in available surface area of solid sourcematerials, (iv) losses of transported source material due tocondensation of the material from the feed stream on cold spots in theflow circuitry, (v) thermal degradation of source material in regions ofthe flow circuitry or in other process system components that are heatedto temperatures above the decomposition temperature of the sourcematerial, and (vii) fluctuations in carrier gas flow rates that resultin corresponding changes of concentration and delivered amount of thesource material.

The foregoing problems involving use of solid and/or liquid sourcematerials has resisted solution, and pose continuing obstacles to thesuccessful utilization of solid and/or liquid source materials forindustrial process use, such as in semiconductor manufacturingprocesses, in which metalorganic compounds and a wide variety of otherreagent materials are of non-gaseous form, and require volatilization,vaporization, sublimation or similar operations to provide gaseous orvapor forms of the material to the process for use therein.

SUMMARY OF THE INVENTION

The present invention relates to apparatuses and methods forphotometrically modulating the delivery of reagents, such as may derivefrom solid and/or liquid sources.

In one aspect, the invention relates to a system adapted to supply agaseous reagent species to a gaseous reagent species-utilizingmanufacturing process region, the system comprising:

(a) a sampling region for analyzing the gaseous reagent species;

(b) a monitor in sensory communication with the sampling region, themonitor being constructed and arranged to responsively generate anoutput signal correlative of presence or concentration of the gaseousreagent species in the sampling region; and

(c) a process controller arranged to receive the output of the monitorand to responsively control one or more process conditions in and/oraffecting the gaseous species-utilizing manufacturing process region.

In another aspect, the invention relates to a gaseous reagent speciessupply system comprising:

a sampling region for analyzing a gaseous reagent species;

an infrared radiation source arranged to emit infrared radiation intothe sampling region; a photometric detector arranged to receive infraredradiation from the sampling region and responsively generate an outputsignal correlative of presence or concentration of the gaseous reagentspecies in the sampling region; at least one infrared radiation filterelement optically coupled between the infrared radiation source and thephotometric detector; and

a process controller arranged to receive the output of the detector andto responsively control one or more process conditions in and/oraffecting the gaseous species-utilizing manufacturing process region.

In another aspect, the invention relates to a system for supplyinggaseous reagent material subject to degradation, the system comprising:

a sampling region for analyzing gaseous reagent material;

a photometric monitor arranged to receive radiation from the samplingregion and responsively generate an output signal correlative ofpresence or concentration of any of (i) at least one species of saidgaseous reagent material, and (ii) at least one decomposition by-productof said gaseous reagent material or a species thereof; and

a control element adapted to receive the output signal to determinewhether degradation of gaseous reagent exceeds a predetermined level.

In another aspect, the invention relates to a process system adapted forprocessing of or with a material therein, said process systemcomprising:

-   -   a sampling region for the material;    -   an infrared photometric monitor constructed and arranged to        transmit infrared radiation through the sampling region and to        responsively generate an output signal correlative of the        material in the sampling region, based on its interaction with        the infrared radiation; and    -   process control means arranged to receive the output of the        infrared photometric monitor and to responsively control one or        more process conditions in and/or affecting the process system.

Another aspect of the invention relates to a method of operating aprocess including processing of or with a material, such methodcomprising exposing the material to infrared radiation and responsivelygenerating with an infrared photometric monitor an output correlative ofthe material, based on its interaction with the infrared radiation; andcontrolling one or more conditions in and/or affecting the process, inresponse to the output.

Other aspects, features and embodiments will be more fully apparent fromthe ensuing disclosure and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a semiconductor manufacturingprocess system including photometrically modulated delivery of reagentfrom a non-gaseous source material, according to one embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS THEREOF

The disclosures of U.S. patent application Ser. No. 11/157,760 filedJun. 21, 2005, U.S. patent application Ser. No. 10/402,759 filed Mar.28, 2003, and U.S. patent application Ser. No. 10/140,848 filed May 8,2002 (issued as U.S. Pat. Nos. 7,058,519, 7,063,097, and 6,617,175,respectively) are hereby incorporated herein by reference in theirrespective entireties, for all purposes.

The present invention relates to utilization of an infrared photometerin a metering arrangement for delivery of reagent, which is useful fordelivery of reagent to a process from a non-gaseous source material. Theinfrared photometer in such arrangement operates as a mass flow meterpermitting an output from the infrared photometer to be employed forresponsively controlling one or more process conditions in and/oraffecting the process system.

More specifically, an infrared photometric monitor is constructed andarranged to transmit infrared radiation through a sampling region, suchas a gas cell, and to responsively generate an output correlative of thematerial in the sampling region, based on its interaction with theinfrared radiation.

The process system in addition to a gas-utilizing facility, such as asemiconductor manufacturing facility, e.g., a semiconductormanufacturing tool, or other process unit adapted for processing of orwith the monitored material therein, advantageously includes a sourcefor such material providing same in gaseous form for monitoring andsubsequent utilization.

The source means may comprise a storage and dispensing vessel for thematerial, or a synthesis or generating unit for such material, or othersuitable supply containers, bulk storage facilities, or the like. Thematerial itself may be in an initially gaseous form, but in a preferredaspect, described more fully hereinafter, the invention isadvantageously employed with materials that are in an initiallynon-gaseous form, e.g., in a liquid state and/or a solid state. Theinvention thus is amenable to implementation for metered delivery ofreagents deriving from source materials that are vaporizable,sublimable, volatilizable, atomizable or otherwise able to be deliveredin a gaseous form. The term “gaseous” in such context includes gases aswell as vapors.

Infrared photometers usefully employed in the practice of the inventioncan be of any suitable type including an infrared radiation source anddetector elements and associated componentry, e.g., infrared radiationmodulation components. Illustrative IR photometers include theCLEANSENS® NDIR photometer commercially available from CS Clean SystemsInc. (Fremont, Calif., USA), the MCS 100E IR photometer commerciallyavailable from SICK AG (Waldkirch, Germany) and the PIR3502 MultiwaveProcess Photometer commercially available from ABB USA (Norwalk, Conn.,USA).

The IR photometric monitor can be installed in-line between the materialsource and the process facility utilizing the gaseous reagent beingmonitored. In application to a semiconductor manufacturing facility, theIR photometric monitor can be situated in-line in the flow circuitrybetween a chemical vapor deposition reactor and a liquid materialvaporizer or bubbler. Where the flow circuitry coupled with the IRphotometric monitor is heated to prevent condensation or freezing of thegaseous reagent being monitored, the IR photometric monitor can beheated to a temperature in the same temperature regime as the flowcircuitry.

By such arrangement, the IR photometric monitor provides atime-dependent concentration profile of the material delivered to thegas-utilizing facility. The IR photometric monitor enables concentrationof the material of interest to be tracked in real time in a qualitativeand quantitative mode. The IR photometric monitor can be arranged tomonitor the reagent species of interest, as well as one or moredecomposition by-products of such reagent species, thereby providing thecapability of detecting unwanted degradation of the reagent, so thatprocess conditions and operation can be responsively altered to suppressany significant decomposition from occurring, when changes in processvariables or settings would otherwise cause such degradation to occur.

The output of the IR photometric monitor can be used to control deliveryparameters such as carrier gas flow rates, vaporizer temperatures,pressures, etc., so that a desired delivery rate of the reagent ofinterest can be achieved and maintained even under fluctuations inprocess conditions and operating modes.

Referring now to the drawing of FIG. 1, there is illustrated a schematicrepresentation of a semiconductor manufacturing process system 10including photometrically modulated delivery of reagent from anon-gaseous source material, according to one embodiment of the presentinvention.

The semiconductor manufacturing process system 10 as illustratedincludes an infrared photometric monitor 12 and a semiconductormanufacturing facility 114. The semiconductor manufacturing facility 114may comprise a semiconductor manufacturing tool such as a chemical vapordeposition (CVD) reactor, an ion implantation chamber, a lithotracksunit, or other processing unit in which a reagent in gaseous form isused.

The gaseous form reagent is supplied to the semiconductor manufacturingfacility 114 from a reagent material source 40.

Reagent material source 40 includes a bubbler vessel 42 containing asource material 62 in liquid form. The bubbler vessel 42 is disposed ina heating jacket 44 that is coupled by electrical line 50 to the heatingjacket controller 46 that in turn is connected by power line 48 to asuitable power source. The heating jacket controller thus is arranged tovary the extent of resistive heating of the vessel 42 by the heatingjacket, by correspondingly varying the current flowed in line 50 to theheating jacket 44.

The liquid 62 in vessel 42 is contacted with a gas in the form ofbubbles 64 by flow of carrier gas, e.g., helium, argon, nitrogen,hydrogen, or other suitable single component or multi-component carriermedium, from carrier gas supply 52 (e.g., a compressed gas cylinder,bulk gas storage tank, or the like) in carrier gas feed line 54containing flow control valve 56 therein to the diptube 60. The diptube60 is open-ended at its lower extremity, thereby permitting the carriergas to bubble through the non-gaseous source material 62 so as toentrain the source material in the carrier gas.

The carrier gas entraining the source material therein disengages fromthe liquid 62 in the headspace 66 of the vessel 42, and is dischargedfrom the vessel in line 68 as a feed stream containing the sourcematerial and the carrier gas. The feed stream flows in line 68,containing flow control valve 70 therein, and traced with a heat tracingelement 92, to the gas sampling chamber 29 of the IR photometric monitor12. The gas sampling chamber 29 is arranged to be heated by heater 96,to provide an input heat flux denoted schematically by arrow Q.

From the gas sampling chamber 29, the feed stream flows in delivery line73, traced with heat tracing element 94, to the semiconductormanufacturing facility 114.

By this arrangement, involving heat tracing of the flow circuitry lines68 and 73, and heating of the gas sampling chamber 29 by the heater 96,the temperature of the feed stream is maintained at a temperature levelthat ensures that no condensation of the source material takes place inthe flow circuitry or the gas sampling chamber.

In the semiconductor manufacturing facility 114, the reagent material isutilized, e.g., as a precursor from which a layer of metal, dielectric,insulator, is deposited under appropriate deposition conditionstherefor, or in other manner as a process gas, cleaning fluid, etc.Effluent gas from the semiconductor manufacturing facility 114, whichmay derive at least in part from the reagent material, is dischargedfrom the semiconductor manufacturing facility 114 in line 73 and flowedto effluent pump 74.

From pump 74, the effluent flows in line 75 to effluent treatment unit76 for abatement of hazardous species therein, e.g., by scrubbing (wetand/or dry scrubbing), catalytic oxidation, incineration, chemicaltreatment, or the like. From the effluent treatment unit 76, the finaltreated effluent is discharged from the process system in vent line 78.

The IR photometric monitor 12 comprises a source of infrared radiation14 whose output radiation 24 is directed along a path illustrativelyshown in dashed line representation. The output radiation 24 ismodulated by diaphragm wheel 16 having openings 18 and 20 therein. Therotation of the wheel 16 thereby permits the radiation to pass throughopening 18 or 20, or alternatively be blocked by the opaque portions ofthe wheel intermediate the openings 18 and 20. The wheel is rotatable bymeans of axle 22, which may be operatively coupled with suitable drivemeans, e.g., an electric motor, generator, gearing assembly, powertake-off assembly, flywheel, etc., to effect rotation of the wheel 16 inthe direction indicated by arrow A in FIG. 1.

The modulated radiation passes through an interference filter 26 that istransmissive of radiation of a specific frequency range. The resultinginfrared radiation enters the sampling chamber 29 through inlet window30 and interacts with the feed stream introduced into the chamber inline 68, thereby altering the radiation so that the radiation passingout of the sampling chamber 29 through exit window 32 to detector 34differs from the radiation passing into the chamber through inlet window30, in a manner that is characteristic of the presence of the reagentspecies in the feed stream at that point in time. The inlet and exitwindows 30 and 32 are formed of IR-transmissive material, such as forexample zinc selenide or other suitable material.

The detector 34 of the IR photometric monitor is coupled by terminals 36to the central processor unit (CPU) 38, to transmit to the CPU a signalthat is correlative of the reagent species of interest and itsconcentration in the feed stream.

The CPU thus is inputted a signal from the IR photometric monitor thatis indicative of the presence and amount of the reagent species ofinterest. The CPU may comprise any suitable means such as a programmablegeneral purpose digital computer, microprocessor, logic unit, integratedcircuitry, etc. that is effective for signal processing of the IRphotometric monitor signal to produce an output for controlling one ormore process conditions in and/or affecting the process system.

In the FIG. 1 system, the CPU is shown as being illustrativelyoperatively linked for control purposes to valve actuator 58 of flowcontrol valve 56, by signal transmission line 82; to valve actuator 72of flow control valve 70, by signal transmission line 84; to the heatingjacket controller 46 by signal transmission line 86; to thesemiconductor manufacturing facility 114 by signal transmission line 88;and to the pump 74 by the signal transmission line 90.

By these respective control linkages, which may be used singly,alternatively, or in various combinations, the photometric monitor andassociated control assembly can be operated to photometrically sense theconcentration of the reagent species of interest in the feed stream andto responsively adjust (i) the flow rate of carrier gas flowed to thebubbler, (ii) the flow rate of the feed stream comprising the carriergas and the reagent species that is flowed to the sampling chamber andthe downstream gas-utilizing process, (iii) the heating of the liquidsource material in the bubbler, (iv) any of the tool settings, processconditions, etc. in the semiconductor manufacturing facility, and/or (v)the pumping rate of the pump used to flow the effluent from thesemiconductor manufacturing facility to the effluent treatment unit.Additionally, or alternatively, the CPU may be arranged to control theheating of material in gaseous or non-gaseous form in the processsystem, e.g., by controlling rate of heat input to the heat tracingelements and the sampling chamber.

It will be appreciated that the specific control linkages shown in FIG.1 are of illustrative character only, and that the monitoring andcontrol system and methodology of the invention can be widely varied tocontrol any specific devices, elements, process units, processconditions, set points, alarm settings, operational modes, cycle times,emergency procedures, etc. based on the photometrically determinedpresence of the reagent species of interest.

Thus, the system is arranged so that the gas-utilizing process iscontrolled in response to the photometric sensing of the reagent speciesof interest, thereby permitting optimal process operation to be achievedand maintained throughout the temporal duration of the gas-utilizingprocess.

It will be further recognized that although the illustrative embodimentof FIG. 1 has been shown as comprising a single IR photometer detectionarrangement, the invention is not thus limited, and that the inventioncontemplates the provision of IR photometric capability for real-timecontemporaneous sensing of multiple specific components of a gaseousfeed stream, and that the CPU may be programmatically arranged toaccommodate such multi-species monitoring by suitable control algorithmsand protocols, so as to provide a highly integrated monitoring andcontrol functionality sensitive to very small variations of any of anumber of components in the source material.

As will be apparent from the foregoing, the present invention providesthe capability for monitoring and control of a gas-utilizing processsystem that permits the efficient use of non-gaseous source materialsfor generating gaseous reagent species, thereby obviating the numerousdeficiencies of prior art approaches for using non-gaseous sourcematerials, as discussed in the Background of the Invention sectionhereof.

While the invention has been described herein with reference to specificaspects, features and embodiments, it will be recognized that theinvention is not thus limited, but is susceptible to implementation innumerous other variations, modifications, and alternative embodiments.Accordingly, the invention is intended to be broadly construed asencompassing such variations, modifications and alternative embodiments,within the spirit and scope of the invention as hereinafter claimed.

1. A system adapted to supply a gaseous reagent species to a gaseousreagent species-utilizing manufacturing process region, the systemcomprising: (a) a sampling region for analyzing the gaseous reagentspecies; (b) a monitor in sensory communication with the samplingregion, the monitor being constructed and arranged to responsivelygenerate an output signal correlative of presence or concentration ofthe gaseous reagent species in the sampling region; and (c) a processcontroller arranged to receive the output of the monitor and toresponsively control one or more process conditions in and/or affectingthe gaseous species-utilizing manufacturing process region.
 2. Thesystem of claim 1, wherein said gaseous reagent species is generatedfrom a non-gaseous species.
 3. The system of claim 2, wherein saidnon-gaseous species is transformed into said gaseous reagent species byvaporizing, subliming, volatilizing, or atomizing.
 4. The system ofclaim 1, wherein said monitor is arranged to monitor any of the reagentspecies of interest, and one or more decomposition by-products of thereagent species.
 5. The system of claim 2, wherein said non-gaseousspecies comprises a solid.
 6. The system of claim 2, wherein saidnon-gaseous species comprises a liquid.
 7. The system of claim 1,comprising a semiconductor manufacturing facility utilizing said gaseousreagent species.
 8. The system of claim 7, wherein the gaseousspecies-utilizing manufacturing process region comprises a vapordeposition unit.
 9. The system of claim 7, wherein the gaseousspecies-utilizing manufacturing process region comprises an ionimplantation unit.
 10. The system of claim 1, wherein said monitorcomprises an infrared photometric monitor constructed and arranged totransmit infrared radiation through the sampling region and toresponsively generate an output signal correlative of presence orconcentration of the gaseous reagent species in the sampling region,based on its interaction with the infrared radiation.
 11. The system ofclaim 1, wherein said process controller is adapted to control adelivery parameter selected from gaseous reagent species flow rate,vaporizer temperature, pressure and combinations thereof.
 12. The systemof claim 2, further comprising a source vessel for said non-gaseousspecies.
 13. The system of claim 2, further comprising a synthesis orgenerating unit for said non-gaseous species.
 14. The system of claim 1,further comprising flow circuitry for said gaseous species.
 15. Thesystem of claim 14, wherein said flow circuitry is heated.
 16. Thesystem of claim 2, wherein said sampling region comprises a gas cell,and said gas cell is heated to prevent said gaseous reagent species fromreverting to said non-gaseous species.
 17. The system of claim 1,wherein said process controller controls flow rate of the gaseousreagent species, temperature of the gaseous reagent species, orutilization of said gaseous reagent species in said gaseous-speciesutilizing manufacturing process region.
 18. A method of manufacturing asemiconductor, the method comprising monitoring a gaseous reagentspecies using the system of claim 1, and responsively controlling one ormore process conditions in and/or affecting the gaseousspecies-utilizing manufacturing process region.
 19. A gaseous reagentspecies supply system comprising: a sampling region for analyzing agaseous reagent species; an infrared radiation source arranged to emitinfrared radiation into the sampling region; a photometric detectorarranged to receive infrared radiation from the sampling region andresponsively generate an output signal correlative of presence orconcentration of the gaseous reagent species in the sampling region; atleast one infrared radiation filter element optically coupled betweenthe infrared radiation source and the photometric detector; and aprocess controller arranged to receive the output of the detector and toresponsively control one or more process conditions in and/or affectingthe gaseous species-utilizing manufacturing process region.
 20. A systemfor supplying gaseous reagent material subject to degradation, thesystem comprising: a sampling region for analyzing gaseous reagentmaterial; a photometric monitor arranged to receive radiation from thesampling region and responsively generate an output signal correlativeof presence or concentration of any of (i) at least one species of saidgaseous reagent material, and (ii) at least one decomposition by-productof said gaseous reagent material or a species thereof; and a controlelement adapted to receive the output signal to determine whetherdegradation of gaseous reagent exceeds a predetermined level.
 21. Amethod utilizing the system of claim 20, the method comprising: flowinggaseous reagent material through the sampling region; photometricallydetecting radiation from the sampling region and responsively generatingan output signal correlative of presence or concentration of any of (i)at least one species of said gaseous reagent material, and (ii) at leastone decomposition by-product of said gaseous reagent material or aspecies thereof; and utilizing the control element to suppressdegradation of said gaseous reagent responsive to said output signal.